Ba felt the full force of the Argentina international's boot in his face as the pair challenged for a 32nd-minute loose ball, which the striker headed inches wide with the score at 0-0.
Benitez: "It was a penalty and a red card for me, the incident.
"In the middle of the park, you just carry on and go back from a free-kick. In the penalty area, you go back, penalty and red card.
"It changed the game. We lost one player with a broken nose, we had one substitution and we had a great reaction in the second half, but it was not enough.
"We are doing a good job in terms of what you can see on the pitch. The team is doing well.
"The team has a very good team spirit and that is really positive, and I am confident that we will finish in the top three. I will do well.
"What I know, what I can see is the team doing well, working hard and when we have this advantage, we have to manage in a better way."